NASA, Oxford Discover Warmer Uranus Than Once Thought

Key points

• Jupiter, Saturn and Neptune each emit more energy than they receive from the sun, which means that they have relatively hot interiors.
• Uranus Flyby of NASA with Voyager 2 in 1986 found the planet colder than expected, which disputed the ideas of the way the planets were formed and evolved.
• However, with advanced computer modeling and a new look at the old data, scientists think that the planet can actually be hotter than expected.

For millennia, astronomers thought Uranus was just a distant star. It was not until the end of the 18th century that Uranus was universally accepted as a planet. To date, the world blued and blue subverts the expectations of scientists, but new research from NASA helps to cancel part of the mystique of the world.

Uranus is unlike any other planet in our solar system. It turns on the side, which means that each post is directly facing the sun during a continuous “summer” of 42 years. Uranus also runs in the opposite direction of all planets except Venus. The data from the NASA Uranus Flyby Voyager 2 Uranus Flyby also suggested that the planet is unusually cold inside, challenging scientists to reconsider fundamental theories of the way the planets have been formed and have evolved in our solar system.

“Since the Flyby of Voyager 2, everyone said that Uranus had no internal warmth,” said Amy Simon, planetary scientist of Goddard Space Flight Center from NASA in Greenbelt, Maryland. “But it was really difficult to explain why, especially compared to other giant planets.”

These projections of Uranus do not come from a single measure of the heat emitted by the planet made by Voyager 2: “It all depends on this point of data,” said Simon. “That’s part of the problem.”

Now, the use of an advanced computer modeling technique and revisiting decades of data, Simon and a team of scientists have found that Uranus actually generates heat, as they reported on May 16 in the monthly opinions of the Royal Astronomical Society Journal.

The internal heat of a planet can be calculated by comparing the amount of energy it receives from the sun to the amount of energy it releases in the space in the form of reflected light and emitted heat. The other giant planets of the solar system – Saturn, Jupiter and Neptune – emit more heat than they receive, which means that additional heat comes from the inside, a large part of the high energy processes that formed the planets 4.5 billion years ago. The amount of heat that a planet gives off could be an indication of its age: the less the heat released from the heat absorbed by the sun is elderly. The planet is elderly.

Uranus stood out from the other planets because he seemed to be as warm as he received, which implies that he did not have his. These intrigued scientists. Some have hypothesized that the planet may be much older than all the others and has completely cooled. Others proposed that a giant collision – the same which could have dropped the planet on its side – exploded the whole heat of Uranus. But none of these hypotheses satisfied the scientists, motivating them to resolve the cold case of Uranus.

“We thought:” Could it really be no internal warmth in Uranus? “,” Said Patrick Irwin, principal author of the newspaper and professor of planetary physics at the University of Oxford in England. “We have done many calculations to see how much Uranus is reflected by Uranus and we realized that he was actually more reflective than people had not estimated.”

The researchers decided to determine the full budget for Uranus’s energy: how much energy it receives from the sun compared to the quantity of sun and to what extent it emits heat. To do this, they had to estimate the total quantity of light reflected by the planet at all angles. “You should see the light that is dispersed on the sides, not only by coming back directly,” said Simon.

To obtain the most precise estimate of Uranus’ energy budget to date, Oxford researchers have developed a computer model that has gathered everything that is known on the atmosphere of Uranus from decades of observations from ground and space telescopes, including the NASA Hubble Spatial Telescope and the installation of NASA infrared telescope. The model included information on the hazes, clouds and seasonal changes from the planet, which all affect the way in which sunlight is reflected and how the heat escapes.

The researchers found that Uranus releases approximately 15% more energy than it receives from the sun, a figure similar to another recent estimate of a distinct study partly funded by NASA which was published on July 14 in geophysical research letters. These studies suggest that Uranus has its own warmth, although much less than its neighbor Neptune, which more emits double the energy it receives.

“Now we have to understand what this quantity of heat means in Uranus, as well as to get better measures,” said Simon.

Decreasing the past of Uranus is useful not only to map the chronology of the formation of the planets of the solar system and migrated to their current orbits, but it also helps scientists to better understand many planets discovered outside the solar system, called exoplanets, the majority of which are the same size as Uranus.

By Emma Friedman
Goddard Space Flight Center of NASA, Greenbelt, MD.